News from The Division of Physics, Mathematics and Astronomyhttp://pma.divisions.caltech.edu/news/rssen-usFri, 22 Feb 2019 15:02:59 +0000JPL News: In Colliding Galaxies, a Pipsqueak Shines Brighthttp://divisions.caltech.edu/sitenewspage-index/jpl-news-colliding-galaxies-pipsqueak-shines-bright-85396<p>In the nearby Whirlpool galaxy and its companion galaxy, M51b, two supermassive black holes heat up and devour surrounding material. These two monsters should be the most luminous X-ray sources in sight, but a new study using observations from&nbsp;<a href="https://www.nustar.caltech.edu/">NuSTAR</a>&nbsp;(Nuclear Spectroscopic Telescope Array)&mdash;a Caltech-led mission managed by the Jet Propulsion Laboratory, which is managed by Caltech for NASA&mdash;shows that a much smaller object is competing with the two behemoths.</p><p>The most stunning features of the Whirlpool galaxy, officially known as M51a, are the two long, star-filled &quot;arms&quot; curling around the galactic center like ribbons. The much smaller M51b clings like a barnacle to the edge of the Whirlpool. Collectively known as M51, the two galaxies are merging.&nbsp;</p><p>At the center of each galaxy is a supermassive black hole millions of times more massive than the sun. The galactic merger should push huge amounts of gas and dust into those black holes and into orbit around them. In turn, the intense gravity of the black holes should cause that orbiting material to heat up and radiate, forming bright disks around each that can outshine all the stars in their galaxies.&nbsp;</p><p>But neither black hole is radiating as brightly in the X-ray range as scientists would expect during a merger.&nbsp;</p><p>&quot;I&#39;m still surprised by this finding,&quot; said study lead author Murray Brightman, a postdoctoral scholar in physics at Caltech. &quot;Galactic mergers are supposed to generate black hole growth, and the evidence of that would be strong emission of high-energy X-rays. But we&#39;re not seeing that here.&quot;</p><p>Read the full story from&nbsp;<a href="https://www.jpl.nasa.gov/news/news.php?release=2019-028">JPL News</a>.&nbsp;</p>http://divisions.caltech.edu/sitenewspage-index/jpl-news-colliding-galaxies-pipsqueak-shines-bright-85396LIGO Receives New Funding to Search for More Extreme Cosmic Eventshttp://divisions.caltech.edu/sitenewspage-index/ligo-receives-new-funding-search-more-extreme-cosmic-events-85349<p>The National Science Foundation (NSF) is awarding Caltech and MIT $20.4 million&nbsp;to upgrade the Laser Interferometer Gravitational-wave Observatory (LIGO), an NSF-funded project that made history in 2015 after making&nbsp;the&nbsp;<a href="http://www.caltech.edu/news/gravitational-waves-detected-100-years-after-einstein-s-prediction-49777">first direct detection of ripples in space and time, called gravitational waves</a>. The investment is part of a joint international effort in collaboration with&nbsp;<a href="https://www.ukri.org/news/us-uk-australia-funding-to-improve-global-gravitational-wave-network/">UK Research and Innovation</a>&nbsp;and the Australian Research Council, which are contributing additional funds. While LIGO is scheduled to turn back on this spring, in its third run of the &quot;Advanced LIGO&quot; phase, the new funding will go toward &quot;Advanced LIGO Plus.&quot; Advanced LIGO Plus is expected to commence operations in 2024 and to increase the volume of deep space the observatory can survey by as much as seven times.</p><p><span style="font-size: 14px;">&quot;I&#39;m extremely excited about the future prospects that the Advanced LIGO Plus upgrade affords gravitational-wave astrophysics,&quot; said Caltech&#39;s David Reitze, executive director of LIGO. &quot;With it we expect to detect gravitational waves from black hole mergers on a daily basis, greatly increasing our understanding of this dark sector of the universe. Gravitational-wave observations of neutron star collisions, now very rare, will become much more frequent, allowing us to more deeply probe the structure of their exotic interiors.&quot;&nbsp;</span></p><p>Since LIGO&#39;s first detection of gravitational waves from the violent collision of two black holes, it has observed&nbsp;<a href="https://www.ligo.caltech.edu/page/four-new-detections-o1-o2-catalog">nine additional black hole mergers and one collision of two dense, dead stars called neutron stars</a>. The&nbsp;<a href="http://www.caltech.edu/news/ligo-and-virgo-make-first-detection-gravitational-waves-produced-colliding-neutron-stars-80082">neutron star merger</a>&nbsp;gave off not just gravitational waves but light waves, detected by dozens of telescopes in space and on the ground. The observations confirmed that heavy elements in our universe, such as platinum and gold, are created in neutron star smashups like this one.</p><p>&quot;This award ensures that NSF&#39;s LIGO, which made the first historic detection of gravitational waves in 2015, will continue to lead in gravitational-wave science for the next decade,&quot; said&nbsp;Anne Kinney, assistant director for NSF&#39;s Mathematical and Physical Sciences Directorate, in a statement. &quot;With improvements to the detectors&mdash;which include techniques from quantum mechanics that refine laser light and new mirror coating technology&mdash;the twin LIGO observatories will significantly increase the number and strength of their detections. Advanced LIGO Plus will reveal gravity at its strongest and matter at its densest in some of the most extreme environments in the cosmos. These detections may reveal secrets from inside supernovae and teach us about extreme physics from the first seconds after the universe&#39;s birth.&quot;</p><p>Michael Zucker, the Advanced LIGO Plus leader and co-principal investigator, and a scientist at the LIGO Laboratory, operated by Caltech and MIT, said, &quot;I&#39;m thrilled that NSF, UK Research, and Innovation and the Australian Research Council are joining forces to make this key investment possible. Advanced LIGO has altered the course of astrophysics with 11&nbsp;confirmed gravitational-wave events over the last three years. Advanced LIGO Plus can expand LIGO&#39;s&nbsp;horizons enough to capture this many events each week, and it will enable powerful new probes of extreme nuclear matter as well as Albert Einstein&#39;s general theory of relativity.&quot;</p><p><em>LIGO is funded by NSF and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF, with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council), and Australia (Australian Research Council-OzGrav) making significant commitments and contributions to the project. More than 1,200 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. A list of additional partners is available at&nbsp;<a href="https://my.ligo.org/census.php">https://my.ligo.org/census.php</a>. LIGO partners with the European&nbsp;<a href="http://www.virgo-gw.eu/">Virgo</a>&nbsp;gravitational-wave detector and its&nbsp;<a href="http://public.virgo-gw.eu/the-virgo-collaboration/">collaboration</a>, consisting of more than 300 physicists and engineers belonging to 28 different European research groups.&nbsp;</em></p>http://divisions.caltech.edu/sitenewspage-index/ligo-receives-new-funding-search-more-extreme-cosmic-events-85349 NASA Selects Caltech-led SPHEREx Space Missionhttp://divisions.caltech.edu/sitenewspage-index/nasa-selects-caltech-led-spherex-space-mission-85328<p>NASA has selected a new Caltech-led space mission that will help astronomers understand both how our universe evolved and how common the ingredients for life are in our galaxy&#39;s planetary systems.</p><p>The Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer mission (SPHEREx) is a planned two-year mission funded at $242 million (not including launch costs) and targeted to launch in 2023. The mission is led by <a href="http://pma.caltech.edu/people/james-j-jamie-bock">James (Jamie) Bock</a>, a professor of physics at Caltech and senior research scientist at the Jet Propulsion Laboratory (JPL), which is managed by Caltech for NASA. SPHEREx is managed by JPL.</p><p>The SPHEREx mission, part of <a href="https://explorers.gsfc.nasa.gov/">NASA&#39;s Explorer Program</a>, will study the history of galaxies and the origin of our universe as well as the origin of water in planetary systems. It will survey the entire sky four times in optical and infrared light, capturing detailed spectral information about hundreds of millions of stars and galaxies.</p><p>&quot;With this announcement, we look forward to building SPHEREx,&quot; says Bock. &quot;SPHEREx will explore the beginning of the universe, the history of galaxy formation, and the role of interstellar ices during the birth of new stars and planets, while providing a unique all-sky data set for astronomy.&quot;</p><p>&quot;We&#39;re all very excited to continue our tradition of Caltech-JPL partnerships on astrophysics Explorer missions, starting with <a href="http://www.galex.caltech.edu/">GALEX</a>, then <a href="https://www.nustar.caltech.edu/">NuSTAR</a>, and now <a href="http://spherex.caltech.edu/">SPHEREx</a>,&quot; says Fiona Harrison, the Benjamin M. Rosen Professor Physics at Caltech; Kent and Joyce Kresa Leadership Chair, Division of Physics, Mathematics and Astronomy; and the principal investigator of NuSTAR. &quot;Explorers enable cutting-edge science implemented on a rapid timescale. These missions offer our students, postdocs, and young researchers the opportunity to get involved in space missions that they can see launch within their time at Caltech.&quot;</p><p>SPHEREx will survey some galaxies so distant, their light has taken 10 billion years to reach Earth. In the Milky Way, the mission will search for water and organic molecules&mdash;essentials for life as we know it&mdash;in stellar nurseries, regions where stars are born from gas and dust as well as in disks around stars where new planets could be forming. Most of the water available to star-forming systems is actually in the form of ices, and it is thought that interstellar ices delivered water to a young Earth, forming the oceans.</p><p>The mission will create a map of the entire sky in 96 different color bands, far exceeding the color resolution of previous all-sky maps. It also will identify targets for more detailed study by future missions, such as NASA&#39;s James Webb Space Telescope and Wide Field Infrared Survey Telescope.</p><p>&quot;I&#39;m really excited about this new mission,&quot; said NASA administrator Jim Bridenstine in a <a href="http://www.nasa.gov/press-release/nasa-selects-new-mission-to-explore-origins-of-universe">news release</a>. &quot;Not only does it expand the United States&#39; powerful fleet of space-based missions dedicated to uncovering the mysteries of the universe, it is a critical part of a balanced science program that includes missions of various sizes.&quot;</p><p>JPL will develop the mission payload in collaboration with Caltech, which will develop the spacecraft&#39;s science instrument. The SPHEREx data will be made publicly available through IPAC, an astronomy data and science center based at Caltech. Ball Aerospace will develop the spacecraft. The Korea Astronomy and Space Science Institute will provide support for instrument calibration and testing. Scientists from across the U.S. and in South Korea will participate in the science analysis of SPHEREx data.</p><p>For more information about SPHEREx, visit <a href="http://spherex.caltech.edu/">http://spherex.caltech.edu/</a>.</p>http://divisions.caltech.edu/sitenewspage-index/nasa-selects-caltech-led-spherex-space-mission-85328Zwicky Transient Facility Nabs Supernovae, Stars, and Morehttp://divisions.caltech.edu/sitenewspage-index/zwicky-transient-facility-nabs-supernovae-stars-and-more-85230<p>The results are rolling in from Caltech&#39;s newest state-of-the-art sky-surveying camera, which began operations at the Palomar Observatory in March 2018. Called the&nbsp;Zwicky Transient Facility, or ZTF, the new instrument has so far discovered 50 small near-Earth asteroids and more than 1,100 supernovae, and it has observed more than 1 billion stars in the Milky Way galaxy. One of the near-Earth asteroids discovered by ZTF, called&nbsp;<a href="https://www.ztf.caltech.edu/news/asteroid-from-rare-species-sighted-in-the-cosmic-wild">2019 AQ3</a>, has an orbital period of just 165 days, the shortest known &quot;year&quot; for any asteroid.</p><p>&quot;It&#39;s a cornucopia of results,&quot; says&nbsp;<a href="http://pma.divisions.caltech.edu/people/shrinivas-r-shri-kulkarni">Shri Kulkarni</a>, the principal investigator of ZTF and the George Ellery Hale Professor of Astronomy and Planetary Science at Caltech. Recently, several new papers about early results and technical specifications for ZTF were accepted for publication in the journal&nbsp;<em>Publications of the Astronomical Society of the Pacific</em>. &quot;We are up and running and delivering data to the astronomical community. Astronomers are energized.&quot;</p><p>ZTF uses the 48-inch Samuel Oschin Telescope at Palomar to survey the northern skies for anything that explodes, moves, or changes in brightness. Because the ZTF camera covers 240 times the size of the full moon in a single night-sky image, it is discovering the most fleeting, or short-lived, of cosmic events, which were impossible to catch before now.&nbsp;</p><p>&quot;ZTF is surveying the whole northern sky every three nights,&quot; says Kulkarni. &quot;It&#39;s already discovering a few supernovae a night, and we expect that rate to go up.&quot;</p><p>The cost to develop and run ZTF is about $24 million, with about $11 million of the funding coming from the U.S. government via the National Science Foundation (NSF) and the rest coming from an&nbsp;<a href="https://www.ztf.caltech.edu/page/team-members">international collaboration of partners</a>. Additional support comes from the Heising-Simons Foundation, along with Caltech itself.&nbsp;</p><p>&quot;The start of routine operations of ZTF marks a new era in our ability to capture the nightly and hourly changes transpiring in the universe,&quot; says Anne Kinney, NSF assistant director for mathematical and physical sciences. &quot;They are now recording real-time events from distant supernovae to nearby asteroids and are poised to discover the violent mergers and explosions generating gravitational-wave events.&quot;</p><p>Because nearly half of ZTF is paid for by the U.S. government, nearly half of its observations are shared publicly in near-real-time with the astronomy community. When varying, or transient, objects are detected, an automated alert system is activated, sending notices out to astronomers, who then quickly follow up on notable objects of interest using other telescopes, including the 60-inch and 200-inch Hale telescopes at Palomar. An NSF-funded program called&nbsp;<a href="http://growth.caltech.edu/">GROWTH</a>, with 18 international observatories in the Northern Hemisphere, also follows up on the ZTF alerts. &nbsp;&nbsp;</p><p>All data from the ZTF camera are sent via a&nbsp;<a href="http://hpwren.ucsd.edu/index.html">microwave network managed by UC San Diego</a>&nbsp;to&nbsp;<a href="https://www.ipac.caltech.edu/">IPAC</a>, an astronomy center at Caltech that processes and archives up to 4 terabytes of data each night. &quot;This is the first time IPAC has generated real-time alerts from a survey and the first time a survey has made public up to hundreds of thousands of alerts per night,&quot; says&nbsp;<a href="http://legacy.spitzer.caltech.edu/features/p_georgehelou.shtml">George Helou</a>, ZTF co-investigator and executive director of IPAC. Ultimately, the detailed data are also made available to astronomers around the world through IPAC.</p><p>&quot;It takes only 10 to 20 minutes from the time a transient observation is made to the time the alert goes out,&quot; says Matthew Graham, the ZTF project scientist at Caltech. Graham specializes in &quot;big data,&quot; and specifically how to handle and process large streams of astronomical data. &quot;It&#39;s like running a major newsroom. We&#39;ve never operated at this scale before, and handling all the data is quite a feat,&quot; he says.</p><p>Discoveries from ZTF so far include not only new supernovae, binary stars, and asteroids but two black holes caught shredding stars. As stars wander too close to black holes, they can be &quot;tidally disrupted&quot; by the gravity of the black hole and stretched into oblivion. Graham says that he and the team working on the tidal disruption data, led by Suvi Gezari of the University of Maryland, got fed up with referring to the technical names for the objects, consisting of long strings of numbers. &quot;We decided to nickname them Ned Stark and Jon Snow, after&nbsp;<em>Game of Thrones&nbsp;</em>characters,&quot; he says.</p><p>ZTF also caught two near-Earth asteroids,&nbsp;2018 NX and 2018 NW, that zipped by Earth at&nbsp;distances of only 72,000 miles and 76,000 miles away, respectively, or approximately a third of the distance between Earth and the moon. These discoveries were enabled by the NSF-funded GROWTH program.</p><p>On January 4, 2019, ZTF caught the near-Earth asteroid&nbsp;2019 AQ3. &quot;This&nbsp;is one of the largest asteroids with an orbit entirely within the orbit of Earth&mdash;a very rare species,&quot; says Quanzhi Ye, a postdoctoral scholar at IPAC who first spotted the asteroid in the ZTF data.&nbsp;</p><p><a href="http://www.pma.caltech.edu/people/thomas-a-tom-prince">Tom Prince</a>, one of the co-investigators of ZTF and the Ira S. Bowen Professor of Physics at Caltech, says that the instrument is particularly adept at identifying new gravitational-wave sources&mdash;in particular, pairs of compact stars like white dwarfs&mdash;that will be observed with future space-based gravitational-wave detectors.&nbsp;&nbsp;</p><p><span style="font-size: 14px;">&quot;Because we cover so much sky so often, we can find these rare exotic binary systems that contain two white dwarf stars, each about the size of Earth but about half the mass of our sun. Their orbits are predicted to become smaller and smaller because of the loss of energy due to gravitational waves.&quot;</span></p><p><span style="font-size: 14px;">ZTF is also laying the groundwork for the future NSF-funded Large Synoptic Survey Telescope (LSST), which will, in every exposure, scan a volume of sky 13 times larger than that scanned by ZTF. LSST is scheduled to begin operations in 2022.&nbsp;</span></p><p>&quot;The same alert techniques that ZTF is developing for international networks of observatories to follow up on its findings will be applied to LSST when it joins the search,&quot; says Kinney.</p><p>The newest ZTF papers are: &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20181207-084047368">The Zwicky Transient Facility: System Overview, Performance, and First Results</a>,&quot; led by Eric Bellm of the University of Washington; &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20190213-135514906">The Zwicky Transient Facility: Science Objectives</a>,&quot; led by Graham; &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20181207-084047467">The Zwicky Transient Facility: Data Processing, Products, and Archive</a>,&quot; led by Frank Masci of IPAC; &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20190131-104830427">Machine Learning for the&nbsp;Zwicky Transient Facility</a>,&quot; led by Ashish Mahabal of Caltech; &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20181127-101530598">The Zwicky Transient Facility Alert Distribution System</a>,&quot; led by Maria Patterson of the University of Washington; &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20190207-103908543">The GROWTH Marshal: A Dynamic Science Portal for Time-domain Astronomy</a>,&quot; led by&nbsp;<a href="http://pma.divisions.caltech.edu/people/mansi-m-kasliwal">Mansi Kasliwal</a>&nbsp;of Caltech; and&nbsp;&quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20181113-112609672">A Morphological Classification Model to Identify Unresolved PanSTARRS Sources: Application in the ZTF Real-Time Pipeline</a><a href="http://resolver.caltech.edu/CaltechAUTHORS:20181113-112609672">,</a>&quot; led by Yutaro Tachibana of Tokyo Institute of Technology and Caltech and Adam Miller of Northwestern University and the Adler Planetarium.&nbsp;</p>http://divisions.caltech.edu/sitenewspage-index/zwicky-transient-facility-nabs-supernovae-stars-and-more-85230When Black Holes Collidehttp://divisions.caltech.edu/sitenewspage-index/when-black-holes-collide-85110<p>One of the most cataclysmic events to occur in the cosmos involves the collision of two black holes. Formed from the deathly collapse of massive stars, black holes are incredibly compact&mdash;a person standing near a stellar-mass black hole would feel gravity about a trillion times more strongly than they would on Earth. When two objects of this extreme density spiral together and merge, a fairly common occurrence in space, they radiate more power than all the stars in the universe.</p><p>&quot;Imagine taking 30 suns and packing them into a region the size of Hawaii. Then take two such objects and accelerate them to half the speed of light and make them collide. This is one of the most violent events in nature,&quot; says Vijay Varma, a graduate student at Caltech.</p><p>In a new study in the January 11 issue of the journal&nbsp;<em>Physical Review Letters</em>, Varma and his colleagues report the most accurate computer model yet of the end stage of black hole mergers, a period when a new, more massive black hole has formed. The model, which was aided by supercomputers and machine-learning, or artificial intelligence (AI) tools, will ultimately help physicists perform more precise tests of Einstein&#39;s general theory of relativity.&nbsp;</p><p><iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" frameborder="0" height="253" src="https://www.youtube.com/embed/7Fwu6Mr_45s" width="450"></iframe></p><p>&quot;We can predict what&#39;s left after a black hole merger&mdash;properties of the final black hole such as its spin and mass&mdash;with an accuracy 10 to 100 times better than what was possible before,&quot; says co-author Davide Gerosa, an&nbsp;Einstein Postdoctoral Fellow in Theoretical Astrophysics at Caltech. &quot;This is important because tests of general relativity depend on how well we can predict the end states of black hole mergers.&quot;</p><p>The research is related to a larger effort to study black holes with LIGO, the Laser Interferometer Gravitational-wave Observatory, which made history in 2015 by making&nbsp;<a href="http://www.caltech.edu/news/gravitational-waves-detected-100-years-after-einstein-s-prediction-49777">the first direct detection of gravitational waves</a>&nbsp;emitted by a black hole merger. Since then, LIGO has detected&nbsp;<a href="https://www.ligo.caltech.edu/page/four-new-detections-o1-o2-catalog">nine additional black hole mergers</a>. Gravitational waves are ripples in space and time, first predicted by Einstein more than 100 years ago. Gravity itself, according to general relativity, is a warping of the fabric of spacetime. When massive objects like black holes accelerate through spacetime, they generate gravitational waves.&nbsp;</p><p>One of the goals of LIGO and the thousands of scientists analyzing its data is to better understand the physics of black hole collisions&mdash;and to use these data, in turn, to assess whether Einstein&#39;s general theory of relativity still holds true under these extreme conditions. A breakdown of the theory might open the door to new types of physics not yet imagined.&nbsp;</p><p>But creating models of colossal events like black hole collisions has proved to be a daunting task. As the colliding black holes become very close to one another, just seconds before the final merger, their gravitational fields and velocities become extreme and the math becomes far too complex for standard analytical approaches.&nbsp;</p><p>&quot;When it comes to modeling these sources, one can use the pen-and-paper approach to solve Einstein&#39;s equations during the early stages of the merger when the black holes are spiraling toward each other,&quot; says Varma. &quot;However, these schemes break down near the merger. Simulations using the equations of general relativity are the only means to predict the outcome of the merger process accurately.&quot;</p><p>That is where supercomputers help out. The team took advantage of nearly 900 black hole merger simulations previously run by the&nbsp;<a href="https://www.black-holes.org/">Simulating eXtreme Spacetimes</a>&nbsp;(SXS) group using the Wheeler supercomputer at Caltech (supported by the Sherman Fairchild Foundation) and the Blue Waters supercomputer&nbsp;at the&nbsp;National Center for Supercomputing Applications&nbsp;(NCSA) at the&nbsp;University of Illinois at Urbana-Champaign.&nbsp;The simulations took 20,000 hours of computing time. The Caltech scientists&#39; new machine-learning program, or algorithm, learned from the simulations and helped create the final model.&nbsp;</p><p>&quot;Now that we have built the new model, you don&#39;t need to take months,&quot; says Varma. &quot;The new model can give you answers about the end state of mergers in milliseconds.&quot;</p><p>The researchers say that their model will be of particular importance in a few years, as LIGO and other next-generation gravitational-wave detectors become more and more precise in their measurements. &quot;Within the next few years or so, gravitational-wave detectors will have less noise,&quot; says Gerosa. &quot;The current models of the final black hole properties won&#39;t be precise enough at that stage, and that&#39;s where our new model can really help out.&quot;</p><p>The&nbsp;<em>Physical Review Letters&nbsp;</em>study, titled &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20190110-130026348">High-accuracy mass, spin, and recoil predictions of generic black-hole merger remnants</a>,&quot; was funded by the Sherman Fairchild Foundation, the National Science Foundation, NASA, the Brinson Foundation, and Caltech. Other authors includealumnus Leo Stein (BS &#39;06) of the University of Mississippi and formerly a postdoctoral scholar at Caltech; François Hébert, a postdoctoral scholar at Caltech; and Hao Zhang of the University of Pennsylvania and formerly a Summer Undergraduate Research Fellow (SURF) at Caltech.&nbsp;</p>http://divisions.caltech.edu/sitenewspage-index/when-black-holes-collide-85110What Astronomers are Gleaning from a Big Blast Called "Cow"http://divisions.caltech.edu/sitenewspage-index/what-astronomers-are-gleaning-big-blast-called-cow-84911<p>On June 16, 2018, a brilliant stellar explosion unlike any seen before went off in the skies, quickly capturing the attention of astronomers around the globe. First spotted by the&nbsp;<a href="http://www.ifa.hawaii.edu/info/press-releases/ATLAS/">ATLAS</a>&nbsp;survey in Hawaii, the event was dubbed AT2018cow through a randomized naming system, and soon earned the nickname &quot;Cow.&quot; Just three days after exploding, Cow had become 10 times brighter than a typical supernova&mdash;a powerful explosion that heralds the death of a massive star.</p><p>&quot;We still don&#39;t know what this is, although it is one of the most intensely studied cosmic events in history,&quot; says Anna Ho (MS &#39;17), a graduate student at Caltech and lead author of a new study about the event. Cow was likely a supernova, she says, although some scientists have proposed that it instead may have been caused by a black hole ripping apart a type of star called a white dwarf.&nbsp;</p><p>In the hours, days, and weeks after the event, telescopes on the ground and in space set their sights on Cow, witnessing a dramatic increase in brightness across the electromagnetic spectrum, from high-energy X-rays to low-energy radio waves. Ho and her colleagues observed millimeter-wave light, which is slightly higher in energy than radio waves.&nbsp;</p><p>&quot;We&#39;ve never seen a supernova this bright in millimeter waves,&quot; she says. &quot;We were shocked.&quot;&nbsp;</p><p>Ho presented these results on January 10 at the 233rd meeting of the American Astronomical Society in Seattle. She and her team began observing Cow five days after it exploded using the Submillimeter Array in Hawaii, and soon after using the National Science Foundation-funded Atacama Large Millimeter Array (ALMA) in Chile. They observed the event, which has since declined in brightness in millimeter waves, on and off for a total of 80 days.</p><p>Ho says that the millimeter-wave data reveal that a shock wave is traveling outward from the explosion at one-tenth the speed of light. &quot;The millimeter-wave data tell us about the early evolution of these fast-paced events, and about their impact on the environment,&quot; says Ho. By combining the millimeter-wave data with publicly available X-ray data, the team was also able to conclude that Cow is likely &quot;engine-driven,&quot; and that a central object formed from a supernova&mdash;such as a black hole or dense dead star called a magnetar&mdash;was behind the flurry of activity.</p><p>In the future, Ho says that astronomers should be able to observe more real-time cosmic events like this in millimeter wavelengths, thanks to state-of-the-art surveys like ATLAS and Caltech&#39;s Zwicky Transient Facility (ZTF) at Palomar Observatory, which catch these events more quickly than before. &quot;You have to act fast to catch the millimeter waves, but when you do, you are given a new window into what is happening in these brilliant explosions.&quot;</p><p>Caltech research scientist Brian Grefenstette is co-author of another recent study on Cow, led by Raffaella Margutti of the&nbsp;Center for Interdisciplinary Exploration and Research in Astrophysics and Northwestern University. The team used, among other telescopes, NASA&#39;s Nuclear Spectroscopic Telescope Array, or NuSTAR, to observe high-energy X-rays emitted in the explosion. NuSTAR captured an unusual &quot;bump&quot; in the high-energy X-ray spectrum, which also suggests an engine-driven explosion generated by a black hole or magnetar formed in a supernova.&nbsp;</p><p>&quot;Thanks to the agility of the operations team, NuSTAR got on target about a week after Cow was discovered,&quot; says Grefenstette, who is a NuSTAR instrument scientist. &quot;Astronomers think that this may be the first live view of a newborn compact object, such as a black hole, glowing brightly in X-rays. Because it is embedded in the ejecta of the supernova explosion, the engine would normally be hidden from view. The high-energy X-ray observations with NuSTAR are essential to piecing together the puzzle of what happened in this dramatic event.&quot;</p><p>The millimeter-wave study led by Ho, titled, &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20181102-103552766">AT2018cow: a luminous millimeter transient</a>,&quot; is accepted for publication in&nbsp;<em>The Astrophysical Journal</em>. Ho is funded by the Global Relay of Observatories Watching Transients Happen (GROWTH) program. Other Caltech authors include Professor of Theoretical Astrophysics Sterl Phinney; Visiting Associate in Physics Vikram Ravi; the George Ellery Hale Professor of Astronomy and Planetary Science Shri Kulkarni; graduate student Nikita Kamraj, and Assistant Professor of Astronomy Mansi Kasliwal.&nbsp;</p><p>The study led by Margutti with co-author Grefenstette, titled, &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20181102-101636582">An embedded X-ray Source Shines Through the Aspherical AT2018cow: Revealing the Inner Workings of the Most Luminous Fast-Evolving Optical Transients</a>,&quot; is accepted for publication in&nbsp;<em>The Astrophysical Journal</em>.&nbsp;</p><p>NuSTAR is led by Caltech&#39;s&nbsp;Fiona Harrison, the Benjamin M. Rosen Professor of Physics,&nbsp;and managed by the Jet Propulsion Laboratory for NASA&#39;s Science Mission Directorate in Washington. Caltech manages JPL for NASA.</p>http://divisions.caltech.edu/sitenewspage-index/what-astronomers-are-gleaning-big-blast-called-cow-84911Magnetar Mysteries in our Galaxy and Beyondhttp://divisions.caltech.edu/sitenewspage-index/magnetar-mysteries-our-galaxy-and-beyond-84847<p>In a new Caltech-led study, researchers from campus and the Jet Propulsion Laboratory (JPL) have analyzed pulses of radio waves coming from a magnetar&mdash;a rotating, dense, dead star with a strong magnetic field&mdash;that is located near the supermassive black hole at the heart of the Milky Way galaxy. The new research provides clues that magnetars like this one, lying&nbsp;in close proximity to a black hole, could perhaps be linked to the source of&nbsp;&quot;fast radio bursts,&quot; or FRBs. FRBs are high-energy blasts that originate beyond our galaxy but whose exact nature is unknown.</p><p>&quot;Our observations show that a radio magnetar can emit pulses with many of the same characteristics as those seen in some FRBs,&quot; says Caltech graduate student Aaron Pearlman, who presented the results today at the 233rd meeting of the American Astronomical Society in Seattle. &quot;Other astronomers have also proposed that magnetars near black holes could be behind FRBs, but more research is needed to confirm these suspicions.&quot;</p><p>The research team was led by Walid Majid, a visiting associate at Caltech and principal research scientist at JPL, which is managed by Caltech for NASA, and Tom Prince, the Ira S. Bowen Professor of Physics at Caltech. The team looked at the magnetar named PSR J1745-2900, located in the Milky Way&#39;s galactic center, using the largest of NASA&#39;s Deep Space Network radio dishes in Australia. PSR J1745-2900 was initially spotted by NASA&#39;s Swift X-ray telescope, and later determined to be a magnetar by NASA&#39;s Nuclear Spectroscopic Telescope Array (NuSTAR), in 2013.&nbsp;</p><p>&quot;PSR J1745-2900 is an amazing object. It&#39;s a fascinating magnetar, but it also has been used as a probe of the conditions near the Milky Way&#39;s supermassive black hole,&quot; says Fiona Harrison, the Benjamin M. Rosen Professor of Physics at Caltech and the principal investigator of NuSTAR. &quot;It&#39;s interesting that there could be a connection between PSR J1745-2900 and the enigmatic FRBs.&quot;</p><p>Magnetars are a rare subtype of a group of objects called pulsars; pulsars, in turn, belong to a class of rotating dead stars known as neutron stars. Magnetars are thought to be young pulsars that spin more slowly than ordinary pulsars and have much stronger magnetic fields, which suggests that perhaps all pulsars go through a magnetar-like phase in their lifetime.</p><p>The magnetar PSR J1745-2900 is the closest-known pulsar to the supermassive black hole at the center of the galaxy, separated by a distance of only 0.3 light-years, and it is the only pulsar known to be gravitationally bound to the black hole and the environment around it.&nbsp;</p><p>In addition to discovering similarities between the galactic-center magnetar and FRBs, the researchers also gleaned new details about the magnetar&#39;s radio pulses. Using one of the Deep Space Network&#39;s largest radio antennas, the scientists were able to analyze individual pulses emitted by the star every time it rotated, a feat that is very rare in radio studies of pulsars. They found that some pulses were stretched, or broadened, by a larger amount than predicted when compared to previous measurements of the magnetar&#39;s average pulse behavior. Moreover, this behavior varied from pulse to pulse.</p><p>&quot;We are seeing these changes in the individual components of each pulse on a very fast time scale. This behavior is very unusual for a magnetar,&quot; says Pearlman. The radio components, he notes, are separated by only 30 milliseconds on average.</p><p>One theory to explain the signal variability involves clumps of plasma moving at high speeds near the magnetar. Other scientists have proposed that such clumps might exist but, in the new study, the researchers propose that the movement of these clumps may be a possible cause of the observed signal variability. Another theory proposes that the variability is intrinsic to the magnetar itself.&nbsp;</p><p>&quot;Understanding this signal variability will help in future studies of both magnetars and pulsars at the center of our galaxy,&quot; says Pearlman.</p><p>In the future, Pearlman and his colleagues hope to use the Deep Space Network radio dish to solve another outstanding pulsar mystery: Why are there so few pulsars near the galactic center? Their goal is to find a non-magnetar pulsar near the galactic-center black hole.</p><p>&quot;Finding a stable pulsar in a close, gravitationally bound orbit with the supermassive black hole at the galactic center could prove to be the Holy Grail for testing theories of gravity,&quot; says Pearlman. &quot;If we find one, we can do all sorts of new, unprecedented tests of Albert Einstein&#39;s general theory of relativity.&quot;&nbsp;</p><p>The new study, titled, &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20181024-142448369">Pulse Morphology of the Galactic Center Magnetar PSR J1745-2900</a>,&quot;&nbsp;appeared in the October 20, 2018, issue of&nbsp;<em>The Astrophysical Journal&nbsp;</em>and was funded by a Research and Technology Development grant through a contract with NASA; JPL and Caltech&#39;s President&#39;s and Director&#39;s Fund; the Department of Defense; and the National Science Foundation. Other authors include Jonathon Kocz of Caltech and Shinji Horiuchi of the CSIRO (Commonwealth Scientific and Industrial Research Organization) Astronomy &amp; Space Science, Canberra Deep Space Communication Complex.</p>http://divisions.caltech.edu/sitenewspage-index/magnetar-mysteries-our-galaxy-and-beyond-84847Young Star Caught in a Fit of Growthhttp://divisions.caltech.edu/sitenewspage-index/young-star-caught-fit-growth-84666<p>Researchers have discovered a young star in the midst of a rare growth spurt&mdash;a dramatic phase of stellar evolution when matter swirling around a star falls onto the star, bulking up its mass. The star belongs to a class of fitful stars known as FU Ori&#39;s, named after the original member of the group, FU Orionis (the capital letters represent a naming scheme for variable stars, and Orionis refers to its location in the Orion constellation). Typically, these stars, which are less than a few million years old, are hidden behind thick clouds of dust and hard to observe. This new object is only the 25th member of this class found to date and one of only about a dozen caught in the act of an outburst.</p><p>&quot;These FU Ori events are extremely important in our current understanding of the process of star formation but have remained almost mythical because they have been so difficult to observe,&quot; says&nbsp;<a href="http://www.pma.caltech.edu/people/lynne-hillenbrand">Lynne Hillenbrand</a>, professor of astronomy at Caltech and lead author of a new report on the findings appearing in&nbsp;<em>The Astrophysical Journal</em>. &quot;This is actually the first time we&#39;ve ever seen one of these events as it happens in both optical and infrared light, and these data have let us map the movement of material through the disk and onto the star.&quot;</p><p>The newfound star, called Gaia 17bpi, was first spotted by the European Space Agency&#39;s&nbsp;<a href="http://sci.esa.int/gaia/">Gaia</a>&nbsp;satellite, which scans the sky continuously, making precise measurements of stars in visible light. When Gaia spots a change in a star&#39;s brightness, an alert goes out to the astronomy community. A graduate student at the University of Exeter and co-author of the new study, Sam Morrell, was the first to notice that the star had brightened. Other members of the team then followed up and discovered that the star&#39;s brightening had been serendipitously captured in infrared light by NASA&#39;s asteroid-hunting&nbsp;<a href="https://neowise.ipac.caltech.edu/">NEOWISE</a>&nbsp;satellite at the same time that Gaia saw it, as well as one-and-a-half-years earlier.</p><p>&quot;While NEOWISE&#39;s primary mission is detecting nearby solar system objects, it also images all of the background stars and galaxies as it&nbsp;sweeps around the sky every six months,&quot; says co-author Roc Cutri, lead scientist for the NEOWISE Data Center at IPAC, an astronomy and data center at Caltech. &quot;NEOWISE has been surveying in this way for five years now, so it is very effective for&nbsp;detecting changes in the brightness of objects.&quot;</p><p>NASA&#39;s infrared-sensing Spitzer Space Telescope also happened to have witnessed the beginning of the star&#39;s brightening phase twice back in 2014, giving the researchers a bonanza of infrared data.&nbsp;</p><p>The new findings shine light on some of the longstanding mysteries surrounding the evolution of young stars. One unanswered question is: How does a star acquire all of its mass? Stars form from collapsing balls of gas and dust. With time, a disk of material forms around the star, and the star continues to siphon material from this disk. But, according to previous observations, stars do not pull material onto themselves fast enough to reach their final masses. &nbsp;</p><p>Theorists believe that FU Ori events&mdash;in which mass is dumped from the disk onto the star over a total period of about 100 years&mdash;may help solve the riddle. The scientists think that all stars undergo around 10 to 20 or so of these FU Ori events in their lifetimes but, because this stellar phase is often hidden behind dust, the data are limited. &quot;Somebody sketched this scenario on the back of an&nbsp;envelope in the 1980s, and, after all this time, we still haven&#39;t done much better at determining the event rates,&quot; says Hillenbrand.</p><p>The new study shows, with the most detail yet, how material moves from the midrange of a disk, in a region located around 1 astronomical unit from the star, to the star itself. (An astronomical unit is the distance between Earth and the sun.) NEOWISE and Spitzer were the first to pick up signs of the buildup of material in the middle of the disk. As the material started to accumulate in the disk, it warmed up, giving off infrared light. Then, as this material fell onto the star, it heated up even more, giving off visible light, which is what Gaia detected.&nbsp;</p><p>&quot;The material in the middle of the disk builds up in density and becomes unstable,&quot; says Hillenbrand. &quot;Then it drains onto the star, manifesting as an outburst.&quot;&nbsp;</p><p>The researchers used the <a href="http://www.keckobservatory.org">W. M. Keck Observatory</a> and Caltech&#39;s <a href="http://www.astro.caltech.edu/palomar/homepage.html">Palomar Observatory </a>to help confirm the FU Ori nature of the newfound star. Says Hillenbrand, &quot;You can think of Gaia as discovering the initial crime scene, while Keck and Palomar pointed us to the smoking gun.&quot;</p><p>The study is titled, <a href="http://resolver.caltech.edu/CaltechAUTHORS:20181218-090456440">&quot;Gaia 17bpi: An FU Ori Type Outburst.&quot;</a><a>&nbsp;</a>Other authors include: Carlos Contreras Peña and Tim Naylor of the University of Exeter; Michael Kuhn and Luisa Rebull of Caltech; Simon Hodgkin of Cambridge University; Dirk Froebrich of the University of Kent; and Amy Mainzer of JPL.&nbsp;</p>http://divisions.caltech.edu/sitenewspage-index/young-star-caught-fit-growth-84666Caltech's David Reitze Named 2018 AAAS Fellowhttp://divisions.caltech.edu/sitenewspage-index/caltechs-david-reitze-named-2018-aaas-fellow-84516<p>David Reitze, the executive director of the Laser Interferometer Gravitational-wave Observatory (LIGO) and a research professor of physics at Caltech, has been named a fellow of the American Association for the Advancement of Science (AAAS).</p><p>The <a href="https://www.aaas.org/news/aaas-honors-accomplished-scientists-2018-elected-fellows">AAAS has named 416 new members this year</a> for their &quot;scientifically or socially distinguished efforts to advance science or its applications,&quot; according to the AAAS. New fellows will be presented with an official certificate and a gold and blue rosette pin (representing science and engineering, respectively) on February 16 at the 2019 AAAS Annual Meeting in Washington, D.C.</p><p>According to the AAAS nomination, Reitze is being honored for &quot;outstanding leadership of [LIGO] into the era of the discovery of the first gravitational waves.&quot;</p><p>As the executive director of LIGO since 2011, Reitze led the team that made&nbsp;<a href="http://www.caltech.edu/news/gravitational-waves-detected-100-years-after-einstein-s-prediction-49777">the first direct detection of gravitational waves</a>&mdash;ripples in space and time. The gravitational waves were generated 1.3 billion years ago by the collision of two black holes. Since then, under his continued leadership, LIGO has, together with European-based Virgo detector, identified gravitational waves from other powerful cosmic events, including&nbsp;<a href="http://www.caltech.edu/news/ligo-and-virgo-make-first-detection-gravitational-waves-produced-colliding-neutron-stars-80082">the merger of two neutron stars</a>.&nbsp;</p><p>The AAAS has also named two new fellows from the Jet Propulsion Laboratory, which is managed by Caltech for NASA. Michael Janssen is being honored for his &quot;distinguished scientific contributions to the study of planets, comets, sun and cosmic microwave background radiation using ground and space-based radio techniques,&quot; and&nbsp;William Langer for his &quot;exceptional contributions to understanding the physics and chemistry of the Galaxy&#39;s interstellar medium, effected through insightful theoretical modeling, novel observations, and thorough interpretation.&quot;</p>http://divisions.caltech.edu/sitenewspage-index/caltechs-david-reitze-named-2018-aaas-fellow-84516Exoplanet Stepping Stoneshttp://divisions.caltech.edu/sitenewspage-index/exoplanet-stepping-stones-84468<p>Astronomers have gleaned some of the best data yet on the composition of a planet known as HR 8799 c&mdash;a young giant gas planet about seven times the mass of Jupiter that orbits its star every 200 years. The team used state-of-the-art instrumentation at the&nbsp;<a href="http://www.keckobservatory.org/">W. M. Keck Observatory</a>&nbsp;to confirm the existence of water in the planet&#39;s atmosphere as well as a lack of methane. While other researchers had previously made similar measurements of this planet, these new, more robust data demonstrate the power of combining high-resolution spectroscopy with a technique known as adaptive optics, which corrects for the blurring effect of Earth&#39;s atmosphere.</p><p>&quot;This type of technology is exactly what we want to use in the future to look for signs of life on an Earth-like planet. We aren&#39;t there yet, but we are marching ahead,&quot; says Dimitri Mawet, an associate professor of astronomy at Caltech and a research scientist at JPL, which Caltech manages for NASA. He is co-author of a new paper on the findings accepted for publication in&nbsp;<em>The Astronomical Journal</em>. The lead author is Ji Wang, formerly a postdoctoral scholar at Caltech and now an assistant professor at The Ohio State University.</p><p>Taking pictures of planets that orbit other stars&mdash;exoplanets&mdash;is a formidable task. Light from the host stars far outshines the planets, making them difficult to see. More than a dozen exoplanets have been directly imaged so far, including HR 8799 c and three of its planetary companions. In fact, HR 8799 is the only multiple-planet system to have its picture taken. Once an image is obtained, astronomers can use instruments, called spectrometers, to break apart the planet&#39;s light, like a prism turning sunlight into a rainbow, thereby revealing the fingerprints of chemicals. So far, this strategy has been used to learn about the atmospheres of several giant exoplanets.&nbsp;</p><p>The next step is to do the same thing but for smaller planets that are closer to their stars (the closer a planet is to its star and the smaller its size, the harder is it to see). The ultimate goal is to look for chemicals in the atmospheres of Earth-like planets that orbit in the star&#39;s &quot;habitable zone,&quot; including any biosignatures that might indicate life, such as water, oxygen, and methane. Mawet&#39;s group hopes to do just this with an instrument on the upcoming&nbsp;<a href="https://www.tmt.org/">Thirty Meter Telescope</a>, a giant telescope being planned for the late 2020s by several national and international partners, including Caltech.&nbsp;</p><p>But for now, the scientists are perfecting their technique using Keck&mdash;and, in the process, learning about the compositions and dynamics of giant planets.&nbsp;</p><p>&quot;Right now, with Keck, we can already learn about the physics and dynamics of these giant exotic planets, which are nothing like our own solar system planets,&quot; says Wang.&nbsp;</p><p>In the new study, the researchers used an instrument on Keck called NIRSPEC (near-infrared cryogenic echelle spectrograph), a high-resolution spectrometer that works in infrared light. They coupled the instrument with adaptive optics, a method for creating crisper pictures using a guide star in the sky as a means to measure and correct the blurring turbulence of Earth&#39;s atmosphere.&nbsp;</p><p>This is the first time the technique has been demonstrated on directly imaged planets using what is known as the L-band, a type of infrared light with a wavelength of around 3.5 micrometers. This region of the electromagnetic spectrum contains many detailed chemical fingerprints.</p><p>&quot;The L-band has gone largely overlooked before because the sky is brighter at this wavelength,&quot; says Mawet. &quot;If you were an alien with eyes tuned to the L-band, you&#39;d see an extremely bright sky. It&#39;s hard to see exoplanets through this veil.&quot;</p><p>The researchers say that the addition of adaptive optics made the L-band more accessible for the study of the planet HR 8799 c. In their study, they made the most precise measurements yet of the atmospheric constituents of the planet, confirming it has water and lacks methane as previously thought.</p><p>&quot;We are now more certain about the lack of methane in this planet,&quot; says Wang. &quot;This may be due to mixing in the planet&#39;s atmosphere. The methane, which we would expect to be there on the surface, could be diluted if the process of convection is bringing up deeper layers of the planet that don&#39;t have methane.&quot;</p><p>The L-band is also good for making measurements of a planet&#39;s carbon-to-oxygen ratio&mdash;a tracer of where and how a planet forms. Planets form out of swirling disks of material around stars, specifically from a mix of hydrogen-, oxygen-, and carbon-rich molecules, such as water, carbon monoxide, and methane. These molecules freeze out of the planet-forming disks at different distances from the star&mdash;at boundaries called snowlines. By measuring a planet&#39;s carbon-to-oxygen ratio, astronomers can thus learn about its origins.&nbsp;</p><p>Mawet&#39;s team is now gearing up to turn on their newest instrument at Keck, called the Keck Planet Imager and Characterizer (KPIC). The team will also use adaptive optics-aided high-resolution spectroscopy that can see planets that are fainter than HR 8799 c and closer to their stars.&nbsp;</p><p>&quot;KPIC is a springboard to our future Thirty Meter Telescope instrument,&quot; says Mawet. &quot;For now, we are learning a great deal about the myriad ways in which planets in our universe form.&quot; &nbsp;</p><p><em>The Astronomical Journal</em> study, titled, &quot;<a href="http://resolver.caltech.edu/CaltechAUTHORS:20181120-073429737">Detecting Water in the Atmosphere of HR 8799 c with L-band High Dispersion Spectroscopy Aided By Adaptive Optics</a>,&quot; was funded by Caltech. Other authors include Jonathan Fortney and Callie Hood of UC Santa Cruz; Caroline Morley of Harvard University; and Björn Benneke of University of Montreal.</p>http://divisions.caltech.edu/sitenewspage-index/exoplanet-stepping-stones-84468